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8/10/2019 Despre Compost en Pag. 41-50
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o
o
Covered Area for storage
o
separated waste
This
is
a covered area with minimum canopy dimensions 25m x 40 m, total of 1,000 m
2
located next to the hali for waste separation, for disposal of separated bulky household
waste, recyclable materials and baled separated waste. The floor of the building
has
been
levelled
and
incorporated into the surrounding plateau, thus allowing the entire vehicular
traffic and manipulation of materials,
to be
performed at the same level, and transportation
to
be
done by trucks and forklifts. Canopies will
be
constructed of stainless profiles and
aluminium panels.
Hangar for ba/ed waste secondary raw materia/s and hazardous waste
Hangar design
to
be a ground floor, partly open steel structure intended for storage of baled
waste, secondary raw materials and hazardous waste. The layout of facility is in accordance
with its functional - operational requirements. Dimensions of the facility are 52.00x18.00 m
height 5.00 m, with average elevation point of the slab at 106.92 alt. The facility is divided
into two units: hangar for baled waste and recyclables, 41.60x18.00
and
hangar for
hazardous waste 10.40x18.00.
Roof cover
is
single layer aluminium sheet metal with roof pitch of 12.8%. Wall liner
is
aluminium sheet metal, hanged on the facade beams on three sides of the facility, while one
longitudinal side
in
hangar for baled waste
and
recyclables and mainly open. The face side
of hangar is open, without wall lining. The openings on the left are for vehicles' access and
naturallight and ventilation in the facility.
Drainage of atmospheric water from the roof
is
achieved by horizontal and vertical gutters
made of galvanized sheet metal.
Thermo insulation of the facility is not necessary due to the nature of its purpose
2 3 7 Organic matter composting and curing facilities
2 3 7 1 General
An open windrow type composting plan will be designed to handle yard trimmings - green
waste (leaves, grass clippings, tree trimmings, and brush from parks and gardens, wood
waste, sawdust and tree pruning) and the compostable portion of a mixed waste stream (e.g.
yard trimmings, food scraps, scrap paper products,
and
other decomposable organics).
Sledge from the town Waste Water Treatment Plan is planned to be treated in the
composting facilities and
it
is going
to
improve the quality of the produced compost. These
materials are the feedstock or "find" for the composting process.
The composting process, designed
as
part of regional landfill complex "Subotica",
is
based
on using the compostable portion of a mixed waste stream as a feedstock (app.
30
of the
total MSW quantity), having in mind that food scraps includes fruit and vegetable trimmings
and
leftover food, waxed corrugated boxes, napkins,
and
other soiled paper, but excludes
meat, fish, bones, fat, oils, eggs, and animal food waste. Also, if the incoming fresh waste
contains lots of inorganic pollution the quality of the maturated compost will be lower and
less suitable for fertilising purposes. Green/organic waste separation at source or at the
regionallandfill complex "Subotica" is of high priority for composting.
The composting plan for treatment of green and organic waste and mixed municipal waste
(after being separated in the Separation plant), will be built as part of the Works Contract
(i.e. in the first phase of the landfills' exploitation life).
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In this way from the beginning of landfill complex operation, the composting plant will be
used for compost production that can
be
sold as commercial product or
in
case of mixed
municipal waste; this compost would
be
disposed
on
the landfill
as
cover material.
The composting plant should have a total capacity of 20,000 ton per year (incoming raw
material). The development of the composting plant at the Subotica RWMC is based on the
following main design criteria:
the facility will
be
open for 6 days a week resulting
in
300 days/yr;
operating times: 300 days per year, 1 shift with 7 effective hours per day; the
in
put of
organic waste
is
estimated at
65
tons raw material per day;
constant supply, no peak deliveries etc;
the waste originates from separately collected organic waste, compostables from the
separation plant
and
waste water treatment sludge;
humidity of delivered materials
is
50-60%;
the process consists of a composting
and
maturing phase;
a place for storage
o
the material;
a weight reduction of 45%;
an
area of 1.5
to
2,0
ha
is
required.
2 3 7 2 Process description:
o delivery of materials (waste) during the day time;
o material is transported in the reception area by means of front end loaders;
o composting process
in
two stages: composting followed
by
maturing;
o The first stage of the composting process will take place under a roofed area, while
the maturing area is in the open air;
o use of static pile system;
o use a compost turn ng machine to regularly turn the organic material
o concrete or asphalt hard surface
is
provided with a drainage system;
o mechanical processing at reception (shredding, after composting and sieving after
maturing);
o moistening with water (recirculation system).
o Maximum consumption of the electrica energy
is
limited to 6 kWh/m
3
of the raw
materials.
Reception area
C
The material is discharged on a platform. On the unloading area there will always be an Q
employee present to check that no cargoes
are
discharged of which the waste composition
deviates too much from the aimed composition.
In
particular, the amount of organic waste
material
and
unacceptable pollutants will
be
checked.
The waste material
on
the reception platform
is
moved by means of a front-end loader.
Large, bulky material must
be
removed from the waste. First the waste will be manually
screened and large objects will be removed, secondly the larger organic material waste will
be
shredded. The waste stream will
be
brought
to
the composting pile.
In
the reception area a space capable of receiving
and
sieving
65
ton per day
is
required.
With a density of 500 kg/m
3
a total daily volume of 130 m
3
is predicted. When the waste is
stored for a duration of one day at a height of 2
m
approximately 200 m
2
is
required. The
pre-treatment line (shredder) also requires this area and for logistics another
500 m
2
is
anticipated.
It
is therefore estirnated that the reception a rea should
be
at least 1000 m
2
omposting
Set up compostinq fields
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)
'-
Composting includes pulverizing /grinding of material
in
order te bring it
in
contact with air
and water as much as possible: after grinding, the particle size in a pile
is
5 te 6 mm. At the
composting field the material
is
mixed with a quantity of oversized material te guarantee a
porous mixture.
Du
ring the grinding process, different components are mixed
in
order for the
composting mass
te
be mixed well enough.
The following steps consist of mixing different kinds of organic waste
in
order te improve the
C/N ratie and the porosity.
Porosity
Bacteria that are encouraged te grow
in
a compost pile are aerobic (require oxygen). Open
spaces must be maintained te provide oxygen and allow air te penetrate and move through
the pile. ldeally
35 te
50% of the pile volume would be small open spaces
te
allow air
through the pile.
C/N ratie
The proper compost mix requires both carbon ( C ) and nitrogen ( N ) at the proper C/N ratie.
The proper
C/N
ratie will result
in
a composting process that generates little edeur, yet offers
an environment where microorganisms can flourish. Genemlly, a C/N ratie that
is
higher han
25:1 is satisfactory. Mos waste materials ha
ve
a C/N ratie that is toc low te compost. In
order te compost these materials, additives that contain a high C/N ratie must be added.
Mixture produced will be transported
by
loader and tunnel will be filled. Walls are 1.2m high,
and
in
the middle the pile
is
about
3m
high. The size of the tunnel
is B Om
x25,0 m .
Volume of the mass for composting per tunnel is 420m3,
se
each tunnel receives mass for
composting that was collected for about 4 days. (consistency of the material is 700kg/m3).
l composting lasts two months, total volume of the tunnels should be about 6000 m3-
14
tunnels. Construction of the tunnels will be done
in
two phases.
The decomposing processes start
in
the pile which consequently increases
in
temperature.
Piles are stacked by loader and they need te be moistened in order te maintain
an
optimal
humidity level of 50
te
65%. The highest water demand
is in
the first and the third phase
when the processes are most intense. They can be covered with foii
in
order te maintain the
temperature.
After formation of the composting piles and the start of decomposition, microorganisms
quickly use ali the oxygen, especially because the pile is compacted under its own weight
which makes it difficult for new amount of air te reach inside the pile. Therefore the piles are
regularly turned with a windrow-turning machine and air from below is blown into the piles.
The most favourable oxygen amount
is
between 1O and 15%. The time and number of
turnings
are
most often defined
by
temperature monitoring, but they also depend
on
the size
of the pile, material composition and type of turner. The piles are at first turned over every
three
te
five days, and every
15
days
in
the curing period.
Leachate collected from the composting piles will be collected, stored and reused for
recirculation of the compost moisture because of high nutrient content and necessary
microorganisms. Excess leachate can be discharged into the sewage network for further
treatment.
The composting plan
is
situated in a large industrial building te protect rain infiltration and
lower the required water treatment system capacity. The height of the covering construction
is
estimated at 6 m.
aturing step
Post processing stage - shredding and screen
ng
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Post processing
is
normally performed
to
refine the compost produc
to
meet end-use
specifications or market requirements. Sorting and removal operations can be conducted to
remove any remaining large or inorganic particles that could lower the quality of the
compost, or
be
aesthetically displeasing. The same equipment can
be
used in both pre
processing
and
post-processing. After curing, the compost
is
transferred
to
a hammer miii for
further size reduction. An additional stationary rotary drum screen ng device (mesh of 5 mm),
placed
in
composting facility, or mobile drum screens/air separator/wind shifter,
is
then used
to separate non-degraded materials from this compost. This equipment allows effective
cleaning
and
removing of impurities
and
over-sized screened particles, the screen size has
to
be
50-80
mm.
The undersize material
is
the readily-usable produc
and is
transferred to
the storage area. Oversized particles undergo additional shredding and screening. Material
which
is
inorganic or cannot be shredded
is
disposed of
at
the landfill cell. Compost
is
transported with a shovel/wheelloader within compost storage area.
The composted material
is
further sieved (
8/10/2019 Despre Compost en Pag. 41-50
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o
For storage of the compost a space of about 1,000 m
is required. It is expected ha the
produc will be stored to a height of 3
m.
Miscellaneous
esidues
In the reception hali, the sorted pollutants and compost resistant materials are dumped into
roll containers. When full the contents of these roll containers are emptied a the landfill.
lnfrastructure
The facility will be provided with a hardened concrete base. A gutter will be constructed o
intercept and drain off the possible leachate water.
Mass balance
The input of the process is 20,000 ton/year. The incoming organic waste from the waste
separation collection is estimated at 100%. It is expected that the final yield of compost is
approximately 45% of the total organic waste input
and
that the compost has a
70
% dry
fraction of which approximately 30%
is
organic.
2 3 7 3 Total are area requirement
The total area is expected a least 1000 m
2
reception a ea; an area of 3260 m
2
for
composting, 4,800 m
2
for maturing, and 1,000 m
2
for storage. Furthermore an area for
treatment (sieving, shredding) of 500 m
is assumed. lncluding logistics it is expected that
the site needs 1.5 - 2
ha.
Offices and other facili ies are not included as they are included in
the waste management site.
Bagging or
bal ing
of final produc
is
not foreseen because it
is
relatively labour intensive and
therefore costly.
In order o improve the quality of the compost and produce a more valuable commercially
produc , the composting plan should be designed so that it can be expanded in the future, to
receive the domestic wastewater treatment low metal content dewatered sludges from the
Subotica Waste water treatment Plant.
2 3 7 4Air blowers
O
The aerated windrow method takes the piped aeration system a step further, using blowers
to supply air to the composting materials. The blowers provide direct control of the process
and allow larger piles.
No
turn ng or agitation of the materials occurs once the pile
is
formed.
When the pile has been formed properly and where the air supply is sufficient and the
distribution uniform, the active composting period is completed in about three o five weeks.
With the aerated windrow technique, the raw material mixture is piled over a concrete base
which
is
criss-crossed
by
trenches,
in
which wood chips, chopped straw or other very porous
material is placed. The porous base material contains a perforated aeration pipe. The pipe is
connected o a blower, which either pulls or pushes air through the pile.
The initial height of the windrows should be about 1.5-2.5 m depending on: material
porosity, weather conditions, and the reach of the equipment used to build the pile. Extra
height is advantageous
in
the wintertime as it helps retain heat. It may be necessary o top
off the pile with
15
cm of finished compost or bulking agent. The layer of finished compost
protects the surface of the pile from drying, insulates it from heat loss, discourages flies, and
filters ammonia and potential odours generated within the pile.
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The required air flow rates and the choice of blowers and aeration pipe depend
on
how
aeration
is
managed, i.e. how the blower
is
controlled. The blower can be run continuously
or intermittently.
n
the latter case, the control mechanism can
be
a programmed time clock
or a temperature sensor.
Positive pressure aeration shall be applied.
n
this case, the exhaust air leaves the compost
pile over the entire pile surface. Therefore, it is difficult to collect the air for odour treatment.
Where better odour control
is
desired, a thicker outer layer o compost can be used.
Pressure aeration provides better air flow than suction aeration, largely because of the lack
of
an
odour filter. The lower pressure loss results
in
greater air flow at the same blower
power. Therefore, pressure systems can be more effective at cooling the pile and they are
preferred where temperature control is the overriding concern.
Based
on
the mass balance o the process, the contractor will calculate the number, the
size, the capacity and the working pressure of the blowers. There will always
be
a standby
blower provided. The blowers shall be housed
in
a weatherproof enclosure.
2 3 7 5 Shredder
An organics shredder has to precede the composting process, in order to reduce the size of
the compostable material, to levels small enough to enhance the process. It is best for the
shredder to
be
mobile.
n
order to achieve maximum operational flexibility it
is
foreseen that
the shredder shall be a movable shredder type, capable o both shredding bulky garden and
park waste branches, etc.) and performing mixing of structural and soft materials.
Alternative options may be proposed by the Tenderer.
The minimum features o the organic waste shredder/mixer are summarised as follows:
COMPOSTING PLANT
SHREDDER
MINIMUM
REQUIREMENTS
PERFORMANCE AND DESIGN CRITERIA UNIT DATA
Specific weight o input materials
-- organic waste
t
0.6 0.5-0.8)
-- bulky green waste t/m
3
0.3 0.1-0.4)
Throughput capacity
t/h
>20
Shredding action
-- diameter of cross-sectional area mm
50
-- max. edge length
mm
250
The fi led in data sheet sha 1 be annexed t the questionnaire in Volume
1
SECTION
:
DATA SHEETS
COMPOSTING PLANT:
TENDERER/CONTRACTOR
SHREDDER
DESIGN DATA UNIT
DATA
Makeltypelmodel
Throughput capacity:
--maximum
t/h
m
3
lh
....................
Overall dimensions:
overall height m ....................
overall length
m
....................
overall width m
Total weight
T
46
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o
o
Power supply ( diesel)
-
Power rating
KW ....................
Power consumption per ton nes
kWh or
litre/t
Capacity of charging hopper
m3
....................
Height
of
charging hopper loading
M ............. .....
edge
Dimensions of charging opening
mxm
....................
Noise emissions
dB(A)
....................
Durability of the shredding parts
hours ....................
ton nes
2.3. 7.6 Windrow turner straddle type
A windrow turner is necessary to periodically turn the windrows in order to improve the post
composting process. The basic characteristics
of
the windrow turner will be as follows:
COMPOSTING PLANT: WIN ROW
MINIMUM
TURNER
REQUIREMENTS
PERFORMANCE ANO DESIGN CRITERIA
UNIT DATA
Convenience cabin with air-filter
Yes
Windrow width
m min. 5
Windrow height
m
min. 2.5
Capacity
m /h min. 2,000
The fi led in data sheet sha 1 be nnexed
to
the questionnaire in Volume
1
SECTION
6
DATA SHEETS
COMPOSTING PLANT:
WIN ROW
TENDERER/CONTRACTOR
TURNER
DESIGN DATA
UNIT DATA
Make/type/model
-
....................
Capacity, maximum
m
3
/h ....................
Overall dimensions:
ove raii heig ht
m
....................
overall length
m
overall width m
Total weight
T
....................
Windrow height
m
....................
Windrow width
m
Power supply (diesel)
yes/no
....................
Power rating
KW
Power consumption (diesel)
per
m
Litre/m,
lntegrated watering system
yes/no ....................
Noise emissions dB(A)
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2 3 7 7 Post screening
Post screening is necessary ta create a material useful for other than landfilling uses. Post
screening can take place before final cu ring and at times after final cu ring. Thus, it is best for
the screen ta be movable ar self mobile:
COMPOSTING PLANT:
DRUM R
MINIMUM
VIBRATING SIEVE
REQUIREMENTS
PERFORMANCE ANO DESIGN
UNIT DATA
CRITERIA
Rubber wheels
-
Yes
Easy exchangeable screens
-
Yes
lntegrated conveyors for discharge
-
Yes
In-put material, specific weight
tim" 0.4-0.6
Capacity tlh
Min. 10
Mesh size
mm 40
The fi led in data sheet sha 1 be annexed
t
the questionnaire in Volume
1
Section
6
, -
Form61 \
COMPOSTING PLANT:
DRUM R
TENDERER/CONTRACTOR
VIBRATING SIEVE
DESIGN DATA
UNIT
DATA
Make/type/model
Capacity, maximum t/h ....................
m
3
/h
....................
Overall dimensions:
overall height
m
overall length m ....................
overall width m
....................
Total weight
T
Range of speeds
min.
1/min
. ..................
max. 1/min . ..................
Power supply ( diesel}
-
" ......
Power rating kW
....................
Power consumption per ton nes
kW/t
....................
Noise emissions
dB(A)
....................
2 3 7 8 Front end loader
The front end loader is the basic tool for moving materials around the composting plant,
moving windrows and loading final produc . The basic characteristics o the loader will be as
follows:
COMPOSTING PLANT:
FRONT ENO
MINIMUM
LOADER
REQUIREMENTS
PERFORMANCE ANO DESIGN UNIT
DATA
CRITERIA
Rubber wheels -
Yes
Stacker equipped facility
-
Yes
Convenience cabin with air-
-
Yes
filter
48
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o
o
Front shovel minimum
ma
1.5
Lift height minimum
m
3
The fi led in data sheet sha 1 be annexed to the questionnaire in Volume 1 SECTION
DATA SHEETS
COMPOSTING PLANT: FRONT
TENDERER/CONTRACTOR
ENO LOADER
DESIGN DATA
UNIT DATA
Make/type/model
Bucket capacity
m3
....................
Operating weight
T
"
...........
Maximum load
T
....................
Engine rated power
Kw ....................
Emission standard EUROMOT
....................
Fuel tank
Litre
Overall dimensions:
Length
M
Height top of cabin
M
Width over tires
M
....................
Bucket width M
Turning radius
M
Operating height
M
....................
2.3.7.9 Loading Conveyor
Large trucks will be loaded with compost by the front end loader. A loading conveyor at
an
angle to the horizontal will be necessary or loading composting material to smaller trucks.
This can be either a bel or a shaftless screw conveyor
COMPOSTING PLANT: CONVEYORS
MINIMUM
REQUIREMENTS
PERFORMANCE AND DESIGN CRITERIA UNIT DATA
Bel speeds
m/s
max. 1
Angle to the horizontal
Minimum
o
30
Maximum
o
5
Distances between idlers
in charging section
mm max. 300
other section
mm
max. 1,000
lower stand idlers
mm
max. 3,000
The fi led in data sheet sha 1 be nnexed to the questionnaire in Volume 1 SECTION
DATA SHEETS
DATA SHEET
COMPOSTING PLANT: CONVEYORS 1 TENDERER/CONTRACTOR
Please fiii out a separate data sheet or each conveyor
49
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Conveyor Unit Nr., location
and
purpose
Make/type/model
...........................
Bel quality
...............................
DESIGN DATA
UNIT DATA
Conveying capacity
-- average m
3
/h
t/h
--maximum m
3
/h
....................
t/h
....................
Bel speed
from
m/s ...................
to
m/s
....................
....................
Stepwise variable bel speed yes/no ....................
Bel length m
....................
Bel width
mm ....................
Drive power
kW
...............
Power consumption, continuous operation kWh/h
2.3.8 Non-hazardous waste landfill
2.3.8.1 General
The area of the proposed plot for waste disposal is 34.33 ha. The area available for the cells
for waste disposal
is
31.60
ha.
The total area of 31.60 ha
is
divided into 1
O
cells that will be built
in
5 successive phases,
each phase consisting of 2 cells.
Design of the cells for waste disposal assumes that after the cell
is
filled and dosed, wasle
is
dis posed of in next cell which rests on the already completed section. The estimated density
of disposed
and
compacted waste, based
on
the technical details of the selected compactor,
is 800 kg/m'-
The first phase of the regional landfill complex comprises the construction of the first and
second
cell
for waste disposal
and
ali auxiliary facilities, while other phases of construction
of the landfill each include the construction of two new cells (i.e. each phase consists of two
cells). The landfill body will be surrounded by dikes.
2.3.8.2 Dikes channels and movable fence
Surrounding dikes are designed
to
support the stability of the cells and anchoring of the
protective membrane at the top of the landfill body. Fiii
ng
of the cells can start only when the
retaining dike
is
constructed. Dikes are of trapezoidal shape of average height 2
m
with a
crown width of 4.0 m and slopes on the outside of maximum inclination 1:1.5 (towards the
peripheral canal),
and
1:1.5 interna (toward the body ofthe landfill).
In the corridor around landfill body, gravei roads-5 m width should
be
designed. They are
made of materials excavated
on
the site. Disposal of waste in the cells will
be
transported
from the manipulative - service area to the cells by this road. Trucks with waste will drive
down into the cells
by
ramps. One ramp
is
designed per cell. These temporary ramps will
have width of 5
m t
the top
and
slopes of maximum 10%.
Partitioned dikes are the dikes in-between the waste disposal cells
and
are minimum 4 m
wide at the top. These dikes have slopes of 1:
1.5.
They are compacted in layers of 20-30
cm
by
bulldozer
and
vibrating rollers, up to 100 % (Proctor procedure) until the final height
is
50
)
)